AWS_SSO_DELETE_PERMISSION_BOUNDARY

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Summary


Forestall ACL Alias	AWS_SSO_DELETE_PERMISSION_BOUNDARY
Affected Object Types	`AWSIAMUser\|AWSIAMRole\|AWSIAMGroup → AWSPermissionSet`
Exploitation Certainty	High
AWS IAM Action	`sso:DeletePermissionBoundaryFromPermissionSet` + `sso:ProvisionPermissionSet`

Description

Account gate: This edge is only emitted for IAM principals that reside in the Organizations management account or an IAM Identity Center delegated-administrator account (service principal sso.amazonaws.com). Principals in any other member account receive AccessDenied from all SSO Admin APIs regardless of their IAM permissions.

An attacker with sso:DeletePermissionBoundaryFromPermissionSet and sso:ProvisionPermissionSet can remove the Permission Boundary attached to a target Permission Set. Permission Boundaries are a hard cap on effective permissions. Removing one lifts all the restrictions it imposed, and every principal holding that Permission Set gains the full scope of their attached policies.

Edge semantics: (Attacker:AWSIAMUser|AWSIAMRole|AWSIAMGroup) -[AWS_SSO_DELETE_PERMISSION_BOUNDARY]-> (Target:AWSPermissionSet)

Precondition: the target Permission Set must have at least one account assignment (poisonablePsGuids); without an assignment, provisioning has no effect.

Identification

# View the permission boundary of a permission set
aws sso-admin get-permissions-boundary-for-permission-set \
  --instance-arn <instance-arn> \
  --permission-set-arn <permission-set-arn>

# Check if the attacker has the required permissions
aws iam simulate-principal-policy \
  --policy-source-arn <attacker-arn> \
  --action-names sso:DeletePermissionBoundaryFromPermissionSet sso:ProvisionPermissionSet \
  --resource-arns "*"

# List account assignments
aws sso-admin list-account-assignments \
  --instance-arn <instance-arn> \
  --account-id <account-id> \
  --permission-set-arn <permission-set-arn>

Exploitation

# Step 1: Delete the Permission Boundary from the permission set
aws sso-admin delete-permissions-boundary-from-permission-set \
  --instance-arn <instance-arn> \
  --permission-set-arn <permission-set-arn>

# Step 2: Re-provision to propagate the change to all assigned accounts
aws sso-admin provision-permission-set \
  --instance-arn <instance-arn> \
  --permission-set-arn <permission-set-arn> \
  --target-type ALL_PROVISIONED_ACCOUNTS

Mitigation

Restrict sso:DeletePermissionBoundaryFromPermissionSet and sso:ProvisionPermissionSet to dedicated Identity Center administrator roles.
Layer SCPs on top of Permission Boundaries. If a boundary is removed, SCP-level restrictions still hold.
Alert immediately on any DeletePermissionBoundaryFromPermissionSet event in CloudTrail.
Periodically audit all Permission Sets with sensitive assignments to confirm they have active Permission Boundaries.
Require multi-party approval for Permission Set boundary changes through an infrastructure-as-code pipeline.

Detection

CloudTrail Event	Description	Key Fields
`DeletePermissionBoundaryFromPermissionSet`	The Permission Boundary was removed from a Permission Set	`requestParameters.permissionSetArn`, `userIdentity.arn`
`ProvisionPermissionSet`	The Permission Set was re-provisioned to accounts	`requestParameters.permissionSetArn`, `requestParameters.targetType`, `userIdentity.arn`

Alert immediately on any DeletePermissionBoundaryFromPermissionSet event for Permission Sets assigned to accounts with sensitive workloads. Also alert when provisioning follows within a short window.

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